An application of scanning thermal microscopy: Analysis of the thermal properties of plasma-sprayed yttria-stabilized zirconia thermal barrier coating

Yttria-stabilized zirconia coatings were deposited on Ti-6Al-4V substrate by plasma spraying. The thermal properties of the as-sprayed coating were characterized using a scanning thermal microscopy that allows thermal conductivity to be mapped down to the submicrometer scale. The analysis of the thermal properties shows the variations in thermal conductivity with the characteristics of the materials. The relation between microstructural features and thermal conductivity was discussed in correlation with the heat conduction mechanism in different layers. Based on the experiments, the thermal probe was calibrated and the thermal conductivities of the coating and the substrate were estimated. Experimental results and thermal conductivity estimation demonstrate that the SThM analyses can be used as a powerful tool for the thermal property and microstructure analysis of plasma-sprayed thermal barrier coating.